The current invention provides a means to prevent the buildup of wax in hearing aids from clogging the sound outlet, and preventing the sound from the hearing aid from reaching the eardrum of the wearer. Such wax buildup has effectively reduced the use of hearing aids which reside in the ear canal, where wax buildup occurs. As a result of such wax buildup, and the difficulty of cleaning, many users simply stop using their hearing aids.
The present invention provides a solution to the wax problem by covering the speaker orifice with a membrane, which vibrates as a result of sounds generated by the hearing aid and is located at the mouth of the speaker orifice, where accumulated surface wax can be simply wiped or safely brushed off.
Hearing aids for persons with impaired hearing are widely available, with millions of users world wide.
Hearing aids are available in a variety of types, including Custom In the Ear (ITE), In the Canal (ITC) and Completely in the Canal (CIC) instruments. Typically, all types are self-contained; with a miniature microphone, amplifier and transducer speaker inside the instrument carrying amplified sound directly to the ear canal and auditory system. Most hearing aids have an adjustable volume control and are powered by small, replaceable batteries.
The ITC, CIC, or other in-canal types are the subject of this invention. A typical instrument of this type is shown in FIGS. 2a, 2b, and 2c (prior art). Its body is an integrally formed plastic shell consisting generally of three parts: the base 30, midsection 31, and neck 32. When worn the neck is inserted into the ear canal, with the base exposed and visible when the ear is viewed by onlookers.
Within the body of the hearing aid is contained a battery compartment 24, a microphone 44 which receives sound to be amplified, an amplifier 46 whose input is connected to the microphone 44 by wiring (not shown) to amplify the sound picked up by the microphone 44, and a sound transducer 48, or loudspeaker to receive the amplified signal from the amplifier 46 and convert the signal into sound. The frequency characteristics of the hearing aid are generally tailored to approximately compensate for the hearing loss characteristics of the wearer.
The ambient sound enters the microphone through microphone orifice 26, located in the base 30, and the microphone output is amplified, shaped and converted via the speaker to an audio output. This sound is transmitted typically through a flexible tube 50 and through an sound outlet 42 in the neck 32, and thence into the user's ear. The sound outlet 42 is generally but not exclusively cylindrical in shape, with an area rather larger than the tube. The tube 50 is affixed to the shell at point 44 of the neck 32, and may also be affixed to the speaker 48, by adhesive means, heat bonding, or the like. Tube 50 protects speaker 48 during user handling and cleaning. Also present is a breather tube 52, which allows air to circulate within the hearing aid, and allow moisture to exit.
In use this construction has been problematic, due to the tendency of ear wax to cover and/or be inserted into the outlet port, thereby degrading the quality and level of the sound reaching the eardrum from the hearing aid, or, indeed, substantially reducing the intelligibility of the sound from reaching the eardrum so as not to be useful to the user.
The user needs some way to remove the wax, since the manufacturers of these devices do not normally provide a practical means for the generally elder user to do so. The user may receive a brush for this purpose, but the brush is difficult to use effectively, and may even push wax further into the orifice. The user must be careful not to damage the speaker. A number of inventions have attempted to solve this problem by placing baffles and barriers of various types in the sound outlet. These include U.S. Pat. No. D355,702 (Johnson), U.S. Pat. No. 5,278,360 (Carbe), U.S. Pat. No. 4,972,488 (Weiss), U.S. Pat. No. 4,870,689 (Weiss), and U.S. Pat. No. 4,553,627 (Gastmeier).
All of these barriers, however, can still allow some wax to enter, and further make it more difficult to remove wax, once it has appeared within the hearing aid.
The present invention, in contrast, provides an impermeable seal against the entry of wax. This invention is in the form of a membrane which vibrates in response to the sound produced by the hearing aid speaker and is located at the mouth of the exit port where it meets the exterior of the neck. Any wax which adheres to this smooth membrane may be easily wiped off by the user with a brush, cloth or tissue without damaging the speaker. And the membrane, if properly designed, causes little or no attenuation of the sound leaving the hearing aid and entering the ear canal, and further causes little or no distortion of the processed sound, maintaining its frequency characteristics to a high degree of fidelity.